1. Field of the Invention
The present invention relates to a functional ice cream. In particular, it relates to a method for preparation of mulberry leaf powder and ice cream containing thereof.
2. Description of the Related Arts
Recently, increased concern about health has driven people to pick up foods having functionality. Among many useful plants and herbs, mulberry, in particular its leaf, attracts people and researchers, because it is known to exert medicinal effect such as depression of blood sugar level, blood pressure and cholesterol level and anti-oxidation action. It has been reported that mulberry leaf has very low content of lipids while it contains water, carbohydrates, proteins and 25 different kinds of amino acids. Among them, alanine, asparaginic acid and glutamic acid which are useful for eliminating hangover are contained abundantly high, and serine and tyrosine, which improves blood circulation in brain and prevents senile-related symptoms, are contained in amounts of 1.2% and 0.8%, respectively. Furthermore, it is rich in various minerals: 60 times of calcium content, 160 times of iron content and 10 times of sphorous content compared to the minerals contained in radish; and 6 times of calcium content, 2 times of iron content and 1.4 times of potassium content compared to those contained in green tea.
Mulberry leaf was employed for producing tea products, noodle, drinks, liquid extract and the like. However, there is no ice cream containing mulberry leaf powder or extract until now. Taste and softness of ice cream may slightly be changed depending on the milk content, since milk is main ingredient. However, what makes the ice cream palatable foods is flavoring agents such as vanilla, strawberry, chocolates, almond nuts, confectionary or coffee flavors.
Though products having functionality as well as palatability are required to meet the consumer""s recent preference for functional natural foods, it if not easy to make ice cream having both functionality and palatability because ice cream is one of very palatable foods.
Thus, the present inventors made an attempt to produce the mulberry leaf-containing ice cream retaining its original palatability while revealing functionality derived from mulberry leaf. The palatability of ice cream products on the market is largely dependent on the taste and flavor attributed to additives such as vanilla, fruits (e.g., strawberry), chocolates and the like. Since the mulberry leaf has a characteristic smell of xe2x80x9cgreen,xe2x80x9d it is not easy to manufacturing non smelly ice creams, which will attract consumers.
After an extensive research to solve above problems, and as a result thereof, we, the present inventors, found that it was possible to prepare mulberry leaf powder suitable for producing functional, palatable ice cream by blanching mulberry leaf in an aqueous solution containing 0.05-0.5% of sodium bicarbonate.
Mulberry leaf powder of the present invention is prepared by mixing in a ratio of 1:1 a mulberry leaf powder (A) prepared by blanching a mulberry leaf in an aqueous solution containing 0.05-0.5% of sodium bicarbonate, drying and pulverizing said mulberry leaf to give a powder of 100-300 mesh and a mulberry leaf powder (B) prepared by pretreating a mulberry leaf with N2 gas and pulverizing said mulberry leaf to give a powder of 100-300 mesh.
And, the mulberry leaf ice cream of the present invention is prepared by a method comprising the steps of:
(a) preparing and blanching a mulberry leaf in an aqueous solution containing 0.05-0.5% of sodium bicarbonate, and drying and pulverizing said mulberry leaf to give a powder of 100-300 mesh;
(b) mixing said mulberry leaf powder from said step (a) with mulberry leaf powder prepared by a process comprising pretreating a mulberry leaf with N2 gas and pulverizing said N2 gas-pretreated mulberry leaf to give a powder of 100-300 mesh, wherein the blanched mulberry leaf powder from step (a) and the N2 gas-pretreated mulberry powder are mixed in a ratio of 1:1;
(c) preparing a mix base for ice cream and homogenizing it;
(d) mixing said homogenized mix base with the mulberry leaf powder resulting from step (b) and flavors; and
(e) aging the resulting mixture followed by freezing and thickening to give mulberry leaf powder containing ice cream.
The present invention further provides mulberry leaf ice cream prepared by the above method.
The present invention will be described in detail below.
According to the method of the present invention, mulberry leaf is blanched in an aqueous solution containing 0.05-0.5% of sodium bicarbonate to eliminate the xe2x80x9csmellxe2x80x9d of greens while retaining its natural color. Then, it is dried and pulverized to give powder. Although, the particle size of the powder is not particularly limited, it is preferable to make the size of the particles in a range of 100-300 mesh in the light of texture and feel of the final ice cream into which the powder is incorporated.
Because the heat transferred during blanching process easily destroy bio-active ingredients (secondary metabolites) such as rutin and GABA, special treatment (additional treatment) is required. One solution to this problem is to use anaerobically treated mulberry leaf powder. N2 treatment is one of the popular methods. In this method, the blanched mulberry leaf powder can be mixed with the N2-treated powder with the ratio of 1:1.
The mulberry leaf ice cream of the present invention contains mulberry leaf powder or mixed mulberry leaf powder (hereinafter, referred to as xe2x80x9cpowderxe2x80x9d sometimes) in an amount of 0.5xcx9c5% by weight of the total ice cream.
The ice cream mix base which is mixed with the powder is well known to those who are skilled in the art, and, for example, is comprised of skim milk powder, raw cream, sugar, hardened coconut oil and the like. After the mix base is mixed with powder, the resulting mixture is aged and frozen to prepare the final ice cream according to the well-known process.
The typical method for preparation of the ice cream containing mulberry leaf powder will be described in detail hereinafter.
The step (a) is to prepare and blanch mulberry leaf in an aqueous solution containing 0.05xcx9c0.5% of sodium bicarbonate, and dry and pulverize said mulberry leaf to give powder of 100xcx9c300 mesh.
After harvesting mulberry leaves with good quality, they are washed throughly in the water and are blanched in 0.05xcx9c0.5%, preferably in an aqueous solution containing 0.15% of sodium bicarbonate at the approximate temperature of 75xcx9c85xc2x0 C.
Next, after the blanched leaves were washed with cold water, the moisture is eliminated. They are then dried either under a well-ventilated shade or in the drier at the temperature of 65xcx9c68xc2x0 C. for the first 20xcx9c40 minutes and then at the temperature of 45xcx9c50xc2x0 C. after emitting the residual moisture inside the drier.
The pulverization may be carried out by a known method using, for example, ball mill or air jet mill, and the pulverized mulberry leaf particles are filtered to obtain powder of 100xcx9c300 mesh.
The step (b) is to prepare a mix base for ice cream and homogenizing it;
The mix base for palatability of the ice cream contains mixed skim milk powder, high-milled sugar, ice sugar, combined water glucose, emulsifying stabilizer, refined salt and purified water, and optionally raw cream or hardened coconut oil. The mix base is mixed with stirring for 10xcx9c60 minutes at the temperature of 40xcx9c90xc2x0 C. After filtering and homogenizing the mix base under 10xcx9c200 kg/cm2, the mix base is sterilized at the temperature of 70xcx9c100xc2x0 C. for 10xcx9c60 seconds and cooled down to 2xcx9c6xc2x0 C.
The step (c) is to mix said homogenized mix base with said powder and flavors.
After moving the sterilized mix base into tank, the mulberry leaf powder and flavors are added thereto and mixed together.
The step (d) is to age the resulting mixture followed by freezing and thickening to give mulberry leaf powder containing ice cream.
After aging the resulting mixture at the temperature of 1xcx9c10xc2x0 C. for 1xcx9c20 hours, it is frozen at the temperature of xe2x88x924xcx9cxe2x88x928xc2x0 C. and then thickened at the rate of 10xcx9c200%, preferably 50xcx9c150%.
Then the ice cream contents can be packed in a conventional way. For example, an automatic charger is used to pack the contents into a cup-shaped packing container. Inside of the container was made of ethylene resin, which becomes the desired shape at the temperature of xe2x88x924xcx9cxe2x88x926xc2x0 C. The bar-type products, which may contain fillers such as adzuki bean syrups, strawberry syrups and the like, can also be manufactured by packaging and hardening the ice cream contents at the temperature of xe2x88x9238xcx9cxe2x88x9252xc2x0 C. for 30xcx9c90 minutes, and store the ice cream at the temperature of xe2x88x9220xcx9cxe2x88x9230xc2x0 C.